The crystal structures of hexakis(dimethylsilyl)benzene (1) and its tricarbonyl tungsten (2), molybdenum (3) and chromium (4) complexes were determined by X-ray diffraction. Compound1crystallizes in the monoclinic system, space groupP21/cwitha= 11.196(5)A,b= 19.675(9)Å,c= 24.447(8)Å,Z= 8, at 175K. The metal complexes2,3,4are isomorphic; the compounds exhibit trigonal modifications (2t,3t,4t), space groupR3 orR3,Z= 6. Crystal data: (2t)a= 19.044(5)Å,c= 14.343(4)Å, at 193K; (3t)a= 19.056(4)Å,c= 14.633(5)Å, at 298K; (4t)a= 19.047(5)Å,c= 14.144(5)Å, at 193K.The metal complexes were dimorphic; compounds2and3exhibit monoclinic modifications (2m,3m), space groupP21,Z= 2. Crystal data: (2m)a= 11.059(4)Å,b= 13.885(4)Å,c= 11.140(3)Å, β = 114.79(3)°, at 225 K; (3m)a= 11.020(6)Å,b= 13.838(4)Å,c= 11.099(4)Å, β = 114.54(3)°, at 193K.Each of the five structures that were solved and refined (1,2m,2t,3m,4t) exhibit an orientational disorder. The extent of the disordering, measured as the refined occupancy of the minor species, varies for independent molecules within the same asymmetric unit in1, and between isomorphic structures in the trigonal and monoclinic series of2,3, and4.The disorder was accommodated differently in the trigonal and monoclinic modifications. The metal tricarbonyl units adopt a staggered conformation with respect to the side chains. Substantial out-of-plane deviations (>0.2 Å) of the dimethylsilyl groups were observed in all the structures and arene bond alternations were measured in the metal complexes.